In recent years the game of tennis has undergone a great world-wide surge in popularity, particularly in the United States. Existing tennis courts are crowded and the demand for construction of new courts is burgeoning.
Tennis courts have been laid out on many types of surfaces including grass, clay or dirt, asphalt or macadam, concrete, wood, linoleum, brick compositions, and synthetic turf. Wood and linoleum are used primarily for indoor courts. Outdoor courts are generally surfaced with concrete, asphalt, clay or grass.
Concrete and asphalt require very little maintenance, but their initial construction costs are very high. Also, the hard, unyielding surfaces of concrete and asphalt courts cause excessive strain to the legs and feet of players.
Clay courts are less expensive to construct than concrete or asphalt courts, but clay courts require a great deal of maintenance. Periodic rolling, as often as daily under heavy usage, is required to keep the surface true. At intervals, additional clay must be added to worn spots and the entire surface carefully releveled. Moreover, clay courts absorb and hold moisture. A wet clay court may become so soggy that every footstep of the players will leave an impression or footprint on the court surface rendering it unfit for play. After heavy rains, days may pass before a clay court drys out to the extent that it is usable.
It is recognized that conventional clay and dirt tennis court surfaces have comprised some sand. However the art has taught that only minor portions of sand were acceptable because sand provides an unstable surface. Surfaces comprising more than about 40% sand were considered to be very poor playing surfaces. While inclusion of sand does help alleviate muddiness, even with the sand, clay courts can remain unusable for 24 to 48 hours after a storm. It has also been known to apply a light dressing of sand to the surface of a clay tennis court when it is to be rolled when damp so that the clay does not stick to the roller, however the art has always cautioned against using more than an absolute minimum of sand. Small amounts of sand have also been advocated as filler materials for the interstices of aggregate surfaces such as macadam, however it has again been emphasized very strenuously that only minimal amounts may be used or the playing surface will be detrimentally affected.
Grass is the epitome of tennis court surfaces. The great championship courts at Wimbledon, England and Forest Hills, New York have traditionally had grass surfaces. For this reason the world's most prestigious tennis organizations are called lawn tennis associations. A good grass court provides the ideal tennis playing surface. However, grass combines the economic disadvantages of hard surface courts and clay courts in that it is expensive to install and requires an excessive amount of maintenance. Also, continuous play on a grass court over a long period of time is not possible because the turf will wear away until large bare patches of earth appear and because of the need of the turf for water and fertilizer. Thus despite the heavy demand for courts, expensive grass courts must stand idle a significant proportion of the time in order to avoid destruction of the grass court surface. The economic disadvantages of grass courts have become so great that tennis experts foresee the time when grass courts will no longer be used at all. Indeed, in 1975 for the first time, the U.S. Open at Forest Hills, New York was played on a clay surface.
Similar problems of expense of installation and maintenance problems of soggy surfaces after rain and excessive wear of turf after periods of more or less continuous use are likewise encountered in grass playing areas of other athletic games such as baseball, soccer or track.
Attempts have been made to use synthetic turf for athletic playing areas including tennis courts. Prior art synthetic turfs have not, however, provided good playing surfaces because they have an unnatural play character due to the springiness of the surface caused by the resilient backing used with such turfs. Conventional artificial turfs also tend to retain water on the surface preventing their use immediately after a rainstorm. Excessive graininess has also been a very troublesome feature of conventional artificial turfs. Graininess occurs because the pile elements of artificial turf are woven into the backing in a regular fashion, and after a period of use the pile elements all tend to lay down in the same direction thereby resulting in a very unnatural bounce for a ball impacting on the surface. Finally, the unnatural footing provided by conventional artificial turfs has been thought to be conducive to falls and resulting player injuries.